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Under most normal circumstances, Marcus Smart is a rogue element. A successful possession might involve barreling his way into a play to set a hard screen, budging his teammate free before following through with his own cut in the opposite direction. It could set up Smart on the block to muscle a smaller guard, a physical mismatch that tends to make opponents antsy. Boston could swing the ball around the perimeter all the way to Smart, who then wobbles his way through traffic—with his dribble being nearly poked away on several occasions—into a wild layup attempt kept down but by the lip of the rim. The Smart brand is mayhem.

Boston, in the wake of Isaiah Thomas’s season-ending hip injury, requires more. Game 3's 111–108 win saw Smart plunged into the depths of more traditional point guard play, in responsibility if not in style. There wasn’t room for him to be the unexpected cutter at the end of a drawn-out possession. Life without Thomas (or even Terry Rozier) on the floor calls Smart toward more pressing needs.

All of the spiraling motion in Brad Stevens’s offense spares Smart (or really, spares everyone else) from having to pound the ball to generate momentum, but still his game shifted toward initiation in Game 3. His performance on the whole was a rousing success. Not only did Smart bust Cleveland’s coverage by hitting seven of his 10 three-point attempts, but he helped maintain a healthy, humming offense for 42 minutes against the best team in the conference. The two outcomes may have been equally improbable.

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Efforts to score without Thomas on the floor this season had proven to be an exercise in instability. It was a subplot of the Celtics’ play worthy of game-to-game monitoring. Boston has such a wide range of interesting contributors but none who do even remotely the same things as Thomas. A void was created through his brilliance; Thomas was so reliable for the Celtics in the regular season and through much of these playoffs that his removal from a game for even a few minutes too long could swing a win to a loss. Every team with a star creator experiences some version of this, but Boston—due to the makeup of its roster—suffered its effects vividly. Going without Thomas meant scrapping for free-for-all scoring within the motion of the base offense.

Had the Celtics believed Smart was any kind of definitive answer as a fill-in point guard, Stevens wouldn’t have done so much scrambling in search of workable options. Had there been reason to believe that Smart would thrive in this sort of role, the lineup data from the regular season would likely have beared it out. More confusingly, both realities are true: there is a version of Smart that can struggle to start up the offense in a random regular season game and there is a version of Smart that can run a tight ship in an improbable win over the Cavs.

Welcome to the Marcus Smart experience. Hustle is guaranteed. Defense comes standard. Much of the rest is vexing—​indispensable on the right night and completely unreliable on the wrong one. Fortunately for Boston, Smart’s latest “right night” just so happened to be the most desperate moment of their season.

Considering the broader implications of Smart’s place on the team, this is a rare opportunity. Most every pick-and-roll that Smart runs would normally go through Thomas. The long, looping curls designed to get Boston’s point guard a clean three-pointer were not conceived with Smart in mind. But in Game 3 and presumably in Tuesday’s Game 4, Smart works them.

These games can be instructive. Anyone who has watched Smart’s career to this point knows his offense to be inconsistent, but inconsistency is not a binary; we’re still learning about the variance in Smart’s game and where that leaves the Celtics just a year away from his restricted free agency. That Boston also holds the No. 1 pick—and the potential to draft Markelle Fultz or Lonzo Ball—complicates the premise. Finding satisfactory minutes for all four of Thomas, Smart, Avery Bradley, and a star guard prospect would be almost impossible. Paying them all (Thomas, Smart, and Bradley will all be free agents in 2018) market value might be even more so.

Smart’s turn at the head of the offense, then, offers a window for evaluation that Boston wouldn’t have had otherwise. The calculus over whether to trade the No. 1 pick, whether to max Thomas on his next deal, and whether to trade Bradley in the coming months all loops back to Smart in some way. In making those determinations, playoff games like these matter. It means something that the Celtics turned the ball over on just 8.6% of their Game 3 possessions with Smart on the floor. Even if it was just a hot shooing night, it’s helpful to see what it does for the offense when Smart punishes defenders going under his ball screens. There is value in watching him make a strong play with a smart read, even if in relatively straightforward fashion:

There’s nothing in Smart’s game to suggest his play just yearns for more opportunity; fundamentally, he’s a career 29.1% three-point shooter who finishes a rancid 48.1% of his shots at the rim. Even in his best moments, it’s not as if Smart is driving in volume (he logged just six drives in all of Game 3, according to data from SportVu) to repeatedly get into the teeth of the defense. He doesn’t seem quite quick enough with the ball for that kind of living.

But if a team balances the floor around him and mitigates his usage with complementary playmaking, some of the sharp edges to Smart’s game can be wielded in interesting ways. It might all be a bit too random for duty as a full-time starter, but don’t underestimate the compounding value of a bully guard. Overpowering the smallest players on the floor can make a defense deeply uncomfortable, so much so that instinctive over-help or altered matchups can create opportunities elsewhere.

That kind of cross-matching works better for Smart than most other guards, considering he’s largely capable of guarding even larger wings. There is a constant struggle to make opponents actually guard Smart closely on nights when he hasn’t more than doubled his usual three-point percentage. The reason Boston tries so hard is because of all the clever little gambits that Smart uses to make plays and the physicality that makes it more viable.

Smart is, in many ways, constantly grinding against the fiber of the modern NBA. He grinds through enough cuts and rebounds and stops to strike a balance, but it will always be precarious so long as no opponent respects his jumper. Keep in mind: All the triumph of Game 3 could have been upended by Smart missing even a single shot. Great as his performance was, it was rooted in a dramatic improbability in the most unstable part of Smart’s game.

This is why there’s room for Boston’s front office and coaching staff to be fans of Smart but still wind up trading him to ease a positional crunch. Smart’s burden of proof—even in showing he could regularly maintain an offense as a back-up point—is complicated. His play bought his team another game in this series, and all that remains of it offers an extended look at Smart in this particular context we wouldn’t see much of otherwise. Some rough patches are to be expected, as are standout moments. What’s left is to calibrate between them in a way that makes sense of one of the league’s thorniest young talents in advance of Boston drawing its own hard, actionable conclusions.